1. Field of the Invention
The present invention relates generally to a current distribution technique, and more particularly to a current distributor that equally shares the total current.
2. Description of Prior Art
Current techniques available in the conventional current paths having a number of light-emitting diodes provide no notion of how to solve the problem of dividing the current flowing through the current paths evenly.
To copy current between a plurality of current paths, some presently available techniques adopt a current mirror. Conventional current mirror has been developed for providing a constant current. The current mirror has a master current path for providing primary control over the other slave current paths. Each current path comprises a similar transistor.
Referring to FIG. 1, a schematic diagram of a conventional current mirror with a plurality of current channels is shown. Each current channel comprises a number of light-emitting diodes. The transistors are connected in series to the rows of light-emitting diodes, respectively. If transistor is operated in the saturation region, the current into the drain node is ideally identical.
However, when current paths have dissimilar impedances, the drain-to-source voltage across one transistor is not equal to the drain-to-source voltage across other transistor. If the drain-to-source voltage across transistor of any of the slave current paths is smaller than the drain-to-source voltage across transistor of the master current paths, this transistor of the slave current path is possibly driven into the linear region. Thus, the current flowing through the rows of light-emitting diodes will not divide evenly.
Presently available rows of light-emitting diodes have the problems of dissimilar impedances, thereby inducing the possibility of driven transistor into the linear region and current mismatching between the rows of light-emitting diodes.